diff --git a/boil_kettle/mqtt.ino b/boil_kettle/mqtt.ino
index bd63847..f3aeafd 100644
--- a/boil_kettle/mqtt.ino
+++ b/boil_kettle/mqtt.ino
@@ -1,6 +1,6 @@
 void ConnectMQTT() {
-  static char *password = MQTT_PASSWORD;
-  static char *user = MQTT_USER;
+  static const char *password = MQTT_PASSWORD;
+  static const char *user = MQTT_USER;
   Serial.println("connecting MQTT...");
   while (!mqtt_client.connect("brewhouse", user, password)) {
     Serial.print(".");